It will have the same ingredients as the green waste bin at your local amenity site. Locally, that would be vast amounts of leylandii , laurel, all kinds of tree debris, grass mowings from unkempt lawns, rough grass, and everything too awful for those who compost. It will have been shredded, laid in long windrows, watered, turned, and sieved before carting to you. It may have a nutrient value but none will be declared. In most cases it will not provide any viable life form but nobody has tested (well ,reported) for micro-organisms nor toxins.
It will be ideal as a mulch, or soil conditioner. Personally, I would not use it as a compost or apply to any area used for edible crops. I have used it beneath flowering shrubs and hedge plantings. It is available in prepacked bags here(50 litre size?) 3 for £10.